Catheter having an active return-to-straight mechanism

ABSTRACT

Actuators for steerable medical devices are disclosed that not only deflect or steer a portion of a medical device (e.g., a distal portion of a catheter shaft), but also include mechanisms for actively returning the deflected portion of the medical device to an initial configuration (e.g., straight or substantially straight). These active return-to-straight mechanisms may return a catheter shaft from a deflected configuration to a substantially straight configuration throughout a medical procedure, may employ one or more tension members extending along the catheter shaft, and may comprise a gross return actuator and a fine return actuator. For example, the gross return actuator may be configured to partially reverse the deflection of the distal portion of the catheter; and the fine return actuator may be configured to continue reversing the deflection. The gross return actuator may automatically trigger or actuate (mechanically or electromechanically) the fine return actuator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application No.61/884,897, filed 30 Sep. 2013, which is hereby incorporated byreference as though fully set forth herein.

BACKGROUND

a. Field

The instant disclosure relates to actuators for steerable medicaldevices. In particular, the disclosure relates to actuators comprisingactive return-to-straight mechanisms employing one or more tensionmembers.

b. Background Art

Electrophysiology catheters are used in a variety of diagnostic,therapeutic, and/or mapping and ablative procedures to diagnose and/orcorrect conditions such as atrial arrhythmias, including for example,ectopic atrial tachycardia, atrial fibrillation, and atrial flutter.Arrhythmias can create a variety of conditions including irregular heartrates, loss of synchronous atrioventricular contractions, and stasis ofblood flow in a chamber of a heart, which can lead to a variety ofsymptomatic and asymptomatic ailments and even death.

Typically, a catheter is deployed and manipulated through a patient'svasculature to the intended site, for example, a site within a patient'sheart. The catheter typically carries one or more electrodes that can beused for cardiac mapping or diagnosis, ablation, and/or other therapydelivery modes, or both, for example. Once at the intended site,treatment can include, for example, radio frequency (RF) ablation,cryoablation, laser ablation, chemical ablation, high-intensity focusedultrasound-based ablation, microwave ablation, and/or other ablationtreatments. In some procedures, the catheter imparts ablative energy tocardiac tissue to create one or more lesions in the cardiac tissue.These lesions disrupt undesirable cardiac activation pathways andthereby limit, corral, or otherwise prevent errant conduction signalsthat can form the basis for arrhythmias.

To position a catheter within the body at a desired site, some type ofnavigation must be used, such as using mechanical steering featuresincorporated into the catheter (or an introducer sheath). In someexamples, medical personnel may manually manipulate and/or operate thecatheter using the mechanical steering features.

In order to facilitate the advancement of catheters through a patient'svasculature, the simultaneous application of torque at the proximal endof the catheter and the ability to selectively deflect the distal tip ofthe catheter in a desired direction can permit medical personnel toadjust the direction of advancement of the distal end of the catheterand to selectively position the distal portion of the catheter during anelectrophysiological procedure. The proximal end of the catheter can bemanipulated to guide the catheter through a patient's vasculature. Thedistal tip can be deflected by a pull wire or other tension memberattached or anchored at the distal end of the catheter and extendingproximally to an actuator in a control handle that controls theapplication of tension on the pull wire.

The foregoing discussion is intended only to illustrate the presentfield and should not be taken as a disavowal of claim scope.

BRIEF SUMMARY

It is desirable to be able to ensure that a deflectable portion of acatheter shaft may be returned to a substantially straight configurationwhenever desired throughout a medical procedure, even if the catheterbecomes less responsive as the medical procedure progresses. It is alsodesirable to be able to tailor total deflectability of the catheterdistal portion and, independent of the targeted total deflectability,maintain the ability to return the deflectable distal portion of thecatheter shaft to a substantially straight configuration wheneverdesired.

In one embodiment, an apparatus comprises a deflection actuatorconfigured to cause deflection of a distal portion of a catheter from aninitial position; a first return actuator configured to partiallyreverse the deflection of the distal portion of the catheter; and asecond return actuator configured to continue reversing the deflectionof the distal portion of the catheter towards the initial position.

In another embodiment, a deflectable catheter comprises a cathetershaft, a deflection actuator, and a handle housing that at leastpartially houses the deflection actuator. The catheter shaft comprises ashaft proximal end, a shaft distal end, a shaft deflectable distalportion, and first and second tension members extending from the shaftproximal end to the shaft deflectable distal portion. The deflectionactuator, which is operatively coupled to the first and second tensionmembers, comprises an active return-to-straight mechanism, which itselfcomprises (i) a primary or gross return actuator and (ii) a secondary orfine return actuator.

The foregoing and other aspects, features, details, utilities, andadvantages of the present invention will be apparent by reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a plunger-type catheter without an activereturn-to-straight mechanism, shown with the upper handle housingremoved and with a tip portion in a fully-deflected configuration.

FIG. 2 is an enlarged, fragmentary view of the handle also depicted inFIG. 1, again shown with the upper handle housing removed to show theinner workings of the catheter actuator.

FIG. 3 is an enlarged, fragmentary view of the distal tip section of thecatheter depicted in FIG. 1, showing the catheter tip portion in afully-deflected configuration.

FIG. 4 is a fragmentary, isometric view similar to FIG. 2.

FIG. 5 depicts the catheter also shown in FIGS. 1-4, but in a neutralposition with the plunger fully retracted into the handle.

FIG. 6 is similar to FIG. 2, but depicts the plunger fully retractedinto the handle.

FIG. 7 is similar to FIG. 3, but shows how the catheter tip may notreturn to a straight configuration despite the plunger having returnedto a neutral (i.e., fully-retracted) position.

FIG. 8 is a fragmentary, isometric view similar to FIG. 4, but showingthe plunger in a fully-retracted configuration.

FIG. 9 is a fragmentary, isometric view of a plunger-type mechanism in alower handle housing with the plunger mechanism in a fully-actuatedposition.

FIG. 10 is a fragmentary, isometric view similar to FIG. 9, but showsthe plunger in a fully-retracted or neutral position.

FIG. 11 is similar to FIG. 1, again depicting a plunger-type catheter ina fully-actuated configuration, but in FIG. 11 an activereturn-to-straight mechanism is visible near the proximal end of thehandle.

FIG. 12 is an enlarged, fragmentary view of the handle depicted in FIG.11, with the upper handle housing removed to show the activereturn-to-straight mechanism while the catheter tip is in itsfully-deflected configuration.

FIG. 13 is similar to FIG. 3 and depicts the distal section of thecatheter in a fully-deflected configuration.

FIG. 14 is a fragmentary, isometric view of the catheter in thefully-deflected configuration also shown in FIG. 12.

FIG. 15 is most similar to FIG. 5, but depicts the catheter also shownin FIGS. 11-14 in a semi-neutral portion, wherein the plunger ispartially retracted into the handle housing.

FIG. 16 is an enlarged, fragmentary view of the handle depicted in FIG.15.

FIG. 17 is an enlarged, fragmentary view of the catheter tip portion inits at-rest position also shown in FIG. 15.

FIG. 18 depicts the catheter shown in FIGS. 11-17 with the handle in itsfully-retracted configuration and its distal tip portion in its neutralconfiguration (i.e., straight or substantially straight configuration).

FIG. 19 is an enlarged, fragmentary view of the handle depicted in FIG.18, with the upper handle housing removed and more clearly showing theactive return-to-straight mechanism in its actuated position.

FIG. 20 is an enlarged, fragmentary view of the distal deflectableportion of the catheter shaft depicted in FIG. 18, showing the tipportion of the catheter in its substantially straight configuration andshowing, in phantom, that the active return-to-straight mechanism may bepre-set so as to deflect the distal portion of the catheter slightly inthe opposite direction when the plunger is fully retracted into thehandle housing.

FIG. 21 is a fragmentary, isometric view of the catheter handle in theconfiguration also shown in FIG. 19.

FIG. 22 is an exploded, isometric view of the components comprising thecatheter actuator also shown in FIGS. 11-21.

FIG. 23 is an enlarged, isometric view of the compression ring alsoshown in FIG. 22.

FIG. 24 is a fragmentary, isometric view of the plunger slidably mountedin the lower handle housing in the orientation also shown in FIGS.11-14.

FIG. 25 is a fragmentary, cross-sectional view taken along ling 25-25 ofFIG. 24, showing the plunger assembly mounted in the lower handlehousing, with the active return-to-straight mechanism in an unactuatedconfiguration.

FIG. 26 is a fragmentary, isometric view similar to FIG. 24, but depictsthe plunger assembly and the return-to-straight mechanism when thereturn-to-straight mechanism is actuated as also shown in FIGS. 18-21.

FIG. 27 is a fragmentary, cross-sectional view taken along line 27-27 ofFIG. 26, showing the plunger assembly and the return-to-straightmechanism in the configuration also shown in FIG. 26.

FIG. 28 is a fragmentary, isometric, cross-sectional view of thereturn-to-straight mechanism in its actuated configuration as also shownin, for example, FIGS. 26 and 27.

FIG. 29 is an isometric view of a lever comprising part of thereturn-to-straight mechanism depicted in, for example, FIGS. 12, 14, 16,19, 21, 22, and 24-28.

FIG. 30 is most similar to FIG. 24, but depicts an alternative levercomprising part of an alternative return-to-straight mechanism.

FIG. 31 is most similar to FIG. 26, but depicts the lever of FIG. 30 inan actuated configuration.

FIG. 32 is most similar to FIG. 29, but is an enlarged, isometric viewof the alternative lever also depicted in FIGS. 30 and 31.

FIGS. 33-36 are similar to FIGS. 11-14, respectively, but depict analternative configuration of the return-to-straight mechanism, whereinan alternative lever is pivotably mounted to the lower handle housing.

FIGS. 37-39 are similar to FIGS. 15-17, respectively, but depict theactuator shown to good advantage in FIGS. 34 and 36 when the plunger isin a semi-neutral configuration (i.e., when the plunger is partiallyretraced into the handle housing), before the return-to-straightmechanism also shown in, for example, FIGS. 34 and 36 has been actuated.

FIGS. 40-43 are similar to FIGS. 18-21, respectively, but depict theactuator shown to good advantage in FIGS. 34 and 36 when the plunger isin a neutral configuration (i.e., when the plunger is fully retracedinto the handle housing), after the return-to-straight mechanism shownto good advantage in, for example, FIGS. 34 and 36 has been actuated.

FIG. 44 is a fragmentary view of a catheter handle according to anotherembodiment having an active return-to-straight mechanism.

FIG. 45 is a schematic diagram showing the basic function of thereturn-to-straight mechanism according to some embodiments, wherein theprimary or gross return actuator automatically triggers the secondary orfine return actuator.

FIG. 46 is a fragmentary view of a portion of FIG. 45, representingembodiments where the primary or gross return actuator does not directlytrigger the secondary or fine return actuator.

FIGS. 47-50 are comparable to, for example, FIGS. 33-36, respectively,but depict an active return-to-straight mechanism comprising a second,manual actuator when the catheter shaft is in a fully-deflectedconfiguration (e.g., when the plunger is fully extended from the handlehousing).

FIGS. 51-54 are similar to FIGS. 47-50, respectively, but depict theplunger fully retracted into the handle housing, before the second,manual actuator is actuated.

FIGS. 55-58 are similar to FIGS. 51-54, respectively, but FIGS. 55, 56,and 58 show the second, manual actuator in its fully-actuatedconfiguration, which returns the distal tip portion (or section) of thecatheter to its substantially straight configuration shown in FIGS. 55and 57.

FIGS. 59-62 are most similar to FIGS. 47-50, respectively, but depict analternative, second, manual actuator in an unactuated configuration.

FIGS. 63-66 are most similar to FIGS. 51-54, respectively, with theplunger fully retracted into the handle housing, before the second,manual actuator is actuated.

FIGS. 67-70 are most similar to FIGS. 55-58, respectively, with theplunger fully retracted into the handle housing, but with the second,manual actuator actuated, which places the distal deflectable section ofthe catheter shaft in its substantially straight configuration shown inFIGS. 67 and 69.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Referring first to FIGS. 1-10, an embodiment of a uni-directional,plunger-type catheter 10 that does not have an active return-to-straightmechanism is described first. While various embodiments are describedherein in the context of a uni-directional catheter, it should berecognized that the disclosed principles are equally applicable tocatheters capable of deflecting in more than one direction, where atleast one of the deflections is not configured to deflect in a directionopposite the deflection and beyond its “undeflected” or neutralposition. For example, the principles described herein are alsoapplicable to a catheter configured to deflect from a substantiallystraight configuration (as used herein, the terms “substantiallystraight” and “straight,” as in “return-to-straight,” describe aconfiguration of the catheter shaft wherein the distal tip portion ofthe catheter shaft is aligned with, or substantially aligned with, theportion of the catheter shaft immediately proximal of the distal tipportion) to a first arc in a first plane, and also to deflect from thesubstantially straight configuration to a second arc in a second plane(e.g., 90 degrees apart from the first plane), whereby one or both ofthe deflections are configured such that they do not deflect in oppositedirections in their respective planes significantly beyond thesubstantially-straight orientation. As another example, the principlesdescribed herein are also applicable to a catheter shaft exhibiting somedistal deflection in its “neutral position,” and is configured todeflect the distal portion toward, away from, or otherwise relative tothis pre-deflected neutral position when actuated, and to complete areturn actuation substantially to the initially deflected neutralposition. It should also be noted that the principles disclosed hereinare equally applicable to deflection mechanisms other than plunger-typemechanisms, although various embodiments herein are described in thecontext of an axially-actuated, plunger-type catheter.

FIG. 1 depicts the entire catheter 10 in a fully-actuated configuration,with the plunger assembly 12 fully advanced from (i.e., pushed distallyand fully extended from) the handle housing 14, which fully deflects thedistal tip section 16 of the catheter shaft 18, as shown to goodadvantage in FIGS. 1 and 3. The plunger assembly 12 can be movedproximally and distally into and out of, respectively, the handlehousing 14 as represented by the double-headed arrow 20 in FIG. 2. Inthis configuration, an active deflection element 22 (e.g., an activetension member or pull wire or puller wire or tension strand or tensioncord or tension fiber) has been fully actuated, thereby fully deflectingthe catheter tip section 16. In FIG. 1, and in FIGS. 2 and 4, the upperhandle housing has been removed to reveal certain features inside of thehandle or actuator 24.

As shown in good advantage in FIGS. 2 and 4, with the plunger assembly12 pushed distally as shown, the plunger assembly 12 is in its mostdistal position relative to the sleeve bearings 26, 28 slidablysupporting the plunger assembly in the handle housing 14. A plunger cap30 comprising the proximal part of the plunger assembly 12 may beclearly seen in FIG. 4. A gripper 32 comprising a wire anchor 34 is alsovisible in both FIGS. 2 and 4. At the distal end of the plunger assembly12 is a thumb boss or thumb gripper 36. During use of the catheter, theuser, most likely an electrophysiologist or other physician, willgenerally grip the handle housing with the fingers of one hand and pushor pull on the thumb boss 36 with the thumb of the gripping hand. Asalso shown in FIGS. 2 and 4, distal from the thumb boss is a strainrelief 38, which supports the proximal portion of the catheter shaft 18.As shown to good advantage in FIG. 3, in this configuration, the distalsection 16 of the catheter shaft 18 is fully deflected relative to theshaft longitudinal axis 40. In particular, the angle phi (D) in FIG. 3represents the maximum deflection angle of the distal section 16 of thecatheter shaft 18. In this particular view, the maximum deflection anglephi is approximately 190 degrees. For purposes of the present invention,however, the maximum deflection angle may vary widely.

Referring next most particularly to FIGS. 5-8, further aspects of thecatheter 10 that does not include an active return-to-straight mechanismwill be described. In the configuration shown in FIGS. 5-8, the plungerassembly 12 has been fully retracted into the handle housing 14 as shownto best advantage in FIGS. 6 and 8 (compare, for example, FIG. 2 to FIG.6, or FIG. 4 to FIG. 8). However, as shown in FIGS. 5 and 7, even thoughthe plunger assembly 12 has been pulled fully into the handle housing 14to its maximum extent, the distal section 16 of the catheter shaft 18remains partially deflected relative to the catheter longitudinal axis40 by an angle theta (θ) labeled in FIG. 7.

FIG. 9 is a fragmentary, isometric view of a plunger-type mechanism 12in a handle housing 14A with the plunger assembly 12 in a fully-actuatedposition, similar to what is shown in FIGS. 1-4. In FIG. 9, however, thehandle housing 14A has a configuration that is slightly different fromthe handle housing 14 configuration shown in, for example, FIGS. 2 and4. FIG. 10 is a fragmentary, isometric view similar to FIG. 9, but showsthe plunger assembly 12 in a fully-retracted or neutral position.

In circumstances where it is highly desirable or preferable to be ableto get the distal tip section 16 of the catheter shaft 18 to return to asubstantially-straight configuration rather than merely to the slightlybent configuration depicted in FIGS. 5 and 7, an activereturn-to-straight mechanism, such as those described below, may beutilized.

FIGS. 11-29 depict a uni-directional catheter 10A having an activereturn-to-straight mechanism 42 according to a first embodiment. InFIGS. 11-14, the uni-directional catheter 10A is depicted in itsfully-actuated configuration, with its distal tip section (or shaftdeflectable distal section) 16A in its fully-deflected configuration.The shaft deflectable distal portion starts from a deflectioncommencement point 44 (see, e.g., FIG. 13) located at a proximal end ofthe shaft deflectable distal portion 16A. FIG. 11 depicts the entirecatheter 10A in this fully-actuated configuration, with the upper handlehousing removed to reveal details within the handle 24A. FIG. 12 is anenlarged view of the handle 24A depicted in FIG. 11. In this view, theplunger assembly 12A has been fully advanced distally. In this figure, afirst embodiment of a lever 46 comprising part of the activereturn-to-straight mechanism 42 is depicted in an unactuatedconfiguration and separated by a space from an actuation boss 48 which,in this embodiment, comprises part of (or is mounted onto) a handlehousing 14B. FIG. 13 is an enlarged, fragmentary view of the distal tipsection 16A of the catheter shown in its fully-deflected configuration.FIG. 13 is similar to FIG. 3. FIG. 14 is an isometric, fragmentary viewof the actuator 24A as also shown in FIGS. 11 and 12, and again clearlyshows that the lever 46 of the return-to-straight mechanism 42 has notbeen actuated.

FIGS. 15-17 are most similar and correspond to FIGS. 11-13,respectively. In FIGS. 15-17, however, the plunger assembly 12A has beenpartially retracted into the handle housing 14B. This may be clearlyseen by comparing FIG. 16 to FIG. 12 and noting the distance between thethumb boss 36 and the distal end of the handle housing 14B. Inparticular, in FIG. 16, the thumb boss 36 is closer to the handlehousing 14B then it is in FIG. 12. When the plunger assembly 12A is inthe configuration shown to best advantage in FIG. 16, thereturn-to-straight mechanism 42 has not yet been actuated. For instance,the lever 46 that is pivotably mounted to the proximal end of theplunger assembly 12A has not yet been pivoted away from the plunger cap30A. With the catheter 10A in this configuration, the distal tip section16A of the catheter has returned toward straight from the configurationdepicted in, for example, FIGS. 11 and 13, but the catheter tip section16A remains partially deflected as shown in FIGS. 15 and 17.

Referring next to FIGS. 18-21, activation of an embodiment of the activereturn-to-straight mechanism 42 will be described. FIG. 18 depicts theentire catheter 10A in a neutral position, where the plunger assembly12A is fully retracted into the handle housing 14B and the cathetershaft 18A is substantially straight. FIG. 19 is an enlarged, fragmentaryview of the handle 24A as shown in FIG. 18. Again, the plunger assembly12A is fully retracted into the handle housing in this configuration.This may be clearly seen by comparing, for example, FIG. 19 to FIGS. 12and 16. In particular, in FIG. 19, the thumb boss 36 is closer to thehandle housing 14B then it is in FIGS. 12 and 16.

As shown to good advantage in FIGS. 19 and 21, when the plunger assembly12A is fully retracted, the active return-to-straight mechanism 42 hasbeen actuated. In particular, the actuation boss 48 mounted on (orcomprising an integral part of) the housing 14B has engaged theactuation pin or segment 50 (see, for example, FIG. 29) comprising partof the lever, thereby pivoting the lever 46 about the pivot pin 52 andmoving the tuner drum 54 (see FIG. 29) away from the plunger cap 30A andpulling the inactive deflection element 56 (see FIG. 26) proximally tothereby fully straighten the distal tip section 16A of the cathetershaft 18A to the substantially straight configuration shown in FIGS. 18and 20.

In some embodiments, the return mechanism may be configured to returnthe catheter shaft to a substantially straight position when the useractuation mechanism (e.g., the plunger assembly) has been returned toits neutral position, while in other embodiments, the return mechanismmay be configured to return the catheter shaft to somewhat less thanstraight or somewhat more than straight (i.e., such that the deflectablesection 16A deflects slightly beyond the longitudinal axis of thecatheter shaft). This latter possibility is represented, for example, bythe dash line 58 and the angle gamma (T) in FIG. 20.

By designing the return-to-straight mechanism to be able to deflect thecatheter shaft in the opposite direction, as shown by the dash line 58in FIG. 20, it may be impossible to return the catheter shaft to asubstantially straight configuration during an entire medical procedure.In particular, as the catheter is used during a procedure, itsperformance may degrade as the catheter shaft takes on fluid, or as thepull wires stretch, or as the deflection mechanism wares. Thus, it maybe desirable to design the uni-directional catheter so that it may, atleast at commencement of use, return the deflectable section 16A paststraight by the small angle gamma (γ) shown in FIG. 20 to ensure that aphysician is able to return the catheter shaft 18A to a substantiallystraight configuration throughout the procedure. That is, the activereturn-to-straight mechanism may be designed to ‘over perform’ slightlyat the commencement of a procedure. As may be clearly understood fromlooking at, FIGS. 11-21, this active return-to-straight mechanism isautomatically trigged or actuated as the plunger assembly 12A isretracted into the handle housing 14B. That is, the physician need onlyreturn the plunger assembly (or gross return actuator or primaryactuator) to its neutral position (e.g., fully retract the plungerassembly 12A into the handle housing 14B) to thereby activate the activereturn-to-straight mechanism 42 (or fine return actuator or secondaryactuator), which pulls the distal deflectable section 16A of thecatheter shaft to the substantially straight configuration shown in, forexample, FIGS. 18 and 20.

FIG. 22 is an exploded, isometric view of a catheter handle 24A havingthe active return-to-straight mechanism 42 according to the firstembodiment and also shown to good advantage in FIGS. 12, 14, 16, 19, and21. As shown in FIG. 22, the actuator includes a lower handle housing 60and an upper handle housing 62 having a number of components sandwichedbetween them. As shown in the central portion of this figure, a plungerassembly is slidably mounted in two sleeve bearings 26, 28. At aproximal end of the plunger, a plunger cap 30A is present. The lever 46comprising part of the active return-to-straight mechanism 42 ispivotably mounted to the proximal side of the plunger cap 30A. A levertuner 64 is shown in FIG. 22. In the assembled mechanism, this tuner isthreaded into the tuner drum 54 (see FIG. 29) of the lever to attach theotherwise inactive deflection element 56 to the lever 46.

As also shown in FIG. 22, at the distal end of the plunger 12A, a shaftlug 66 and a strain relief 38 are present, and the thumb boss 36 threadsonto the plunger body 68. The previously-noted gripper 32 and wireanchor 34 are shown in this figure on the mid-section of the plungerassembly 12A. At the proximal end of the handle housing, a connector 70is present. As is also shown to good advantage in FIG. 22, a fluid lumen72 may be present for irrigated configurations. The lower and upperhandle housings 60, 62 are held together by a slip washer 74, acompression ring 76, and a handle cap 78 that threads onto the distalends of the handle housings, and by an assembly ring 80 at the proximalend of the handle housings.

FIG. 23 depicts an enlarged version of one embodiment of the compressionring 76 (also shown in FIG. 22), and more clearly shows a beveled orchamfered inner leading edge 82 of this compression ring. This beveled,inner leading edge helps facilitate smooth movement of the plungerassembly 12A as it is retracted into the handle housing 14B (herecomprising the lower handle housing 60 and the upper handle housing 62).More particularly, the chamfered compression ring 76 may serve as adirectionally dependent frictional force, such that movement of theplunger 12A in one direction has a lesser frictional force than movementof the plunger in an opposite direction. For example, where the beveledinner leading edge 82 of the compression ring faces distally, plungeractuation in the distal direction (e.g., when deflecting the distalshaft) experiences less friction than when the plunger is actuated inthe proximal direction (e.g., when returning the deflection to itsneutral position). The chamfered edge of the compression ring candistort into an airspace, due to the beveled edge, when the plunger ismoved distally. The non-chamfered edge 84 of the compression ring 76abuts one or more constraining layers when the plunger is movedproximally, which results in an increased deflection return forcerelative to the deflection actuation force. This may, for example,facilitate ease of deflection forces while maintaining a deflection“locking” mechanism through a higher return force.

FIGS. 24-29 depict further details of the active return-to-straightmechanism 42 according to the first embodiment. FIGS. 24 and 25 show thelever 46 in its unactuated configuration. As shown to best advantage inFIG. 29, which is an isometric view of the first embodiment of the lever46, separated away from remaining portions of the activereturn-to-straight mechanism, this lever includes a tuner drum 54, apull wire tensioning arm 86, an activation pin or segment 50, a pincarrier segment 88, and a pivot pin 52. As shown in FIGS. 24-28, thelever 46, in this embodiment, is mounted to the plunger cap 30A byfrictionally engaging the lever pivot pin 52 in a pin channel 90extending proximally from the rear surface of the plunger cap 30A. FIGS.25, 27, and 28 clearly show the pivot pin 52 in position in the pinchannel 90.

Referring back to FIGS. 24 and 25, when the active return-to-straightmechanism 42 is in the unactuated configuration, a tuner drum 54 isclose to or against the rear surface (i.e., the proximal surface) of theplunger cap 30A. When the return-to-straight mechanism is actuated, asshown to good advantage in FIGS. 26-28, the actuation boss 48 (part ofthe lower handle housing 60 in this embodiment) presses against thelever actuation segment 50, thereby pivoting the lever 46 proximally(i.e., rightward in FIGS. 26-28), which pulls on the inactive deflectionelement 56 (see, e.g., FIG. 26). Thus, as previously mentioned, in thisconfiguration of the active return-to-straight mechanism 42, when theuser pulls the plunger 12A back into the handle housing to itsfull-retracted or fully-neutral configuration, the activereturn-to-straight mechanism 42 is automatically actuated to tension theinactive deflection element 56, thereby pulling the distal deflectablesection 16A of the catheter shaft 18A to its substantially straightconfiguration shown in, for example, FIGS. 18 and 20.

FIGS. 30-32 are similar to FIGS. 24, 26, and 29, respectively, butdepict a lever 46A according to a second embodiment. As shown to bestadvantage in FIG. 32, the lever 46A according to this embodimentincludes a tuner port 92, a pull wire slot 94, a pull wire tensioningarm 86A, a first elbow 96, an activation segment 50A, a second elbow 98,a pin carrier segment 88A, and a pivot pin 52A. When this lever 46A ofthis second embodiment of an active return-to-straight mechanism 42A isin its unactuated position, as shown to best advantage in FIG. 30, thepull wire tensioning arm 86A rests against or close to the rear surfaceof the plunger cap 30A. When the plunger assembly is fully retractedinto the handle housing as shown in FIG. 31, the actuation boss 48presses against the actuation segment 50A of the lever 46A, therebydriving the pull wire tensioning arm 86A away from the plunger cap 30Band thereby tensioning the inactive deflection element (not shown inFIGS. 31 and 32; but see inactive deflection element 56 in FIG. 26) topull the distal deflectable section 16A of the catheter shaft 18A intothe substantially straight configuration shown, for example, in FIG. 18.

FIGS. 33-43 depict an active return-to-straight mechanism 42B accordingto a third embodiment. In particular, FIGS. 33-36 depict the catheter10B and various enlarged portions of the catheter while the catheter isin a fully-actuated configuration, placing the catheter tip portion 16Ain a fully-deflected configuration. FIGS. 37-39 depict the catheter 10B,and enlarged portions of the catheter, when the plunger assembly 12B isin a semi-neutral position (i.e., a nearly fully-retractedconfiguration). Finally, FIGS. 40-43 depict the catheter 10B and variousenlarged components of the catheter, when the plunger assembly 12B hasbeen fully retracted to a neutral position (i.e., when the plungerassembly has been fully retracted into a handle housing 14C), therebyactuating the active return-to-straight mechanism 42B.

As shown to best advantage in FIGS. 34, 36, 38, 41, and 43, in thisconfiguration, the active return-to-straight mechanism 42B includes alever 46B that is pivotably mounted to the lower handle housing 60B, andan actuation boss 48A extends proximally from the proximal surface ofthe plunger cap 30C. When the steering actuator is fully actuated, asshown in FIGS. 33-36, the distal deflectable section 16A of the cathetershaft 18A is fully deflected, as best shown in FIGS. 33 and 35; and theactuation boss 48A is separated from the lever 46B as shown in FIGS. 34and 36.

When the plunger assembly 12B is then retracted to a semi-neutralposition (i.e., when the plunger assembly is partially retracted intothe handle housing 14C), as shown in FIGS. 37-39, the actuation boss 48Amakes initial contact with the lever 46B. In this configuration, thedistal deflectable section 16A of the catheter shaft 18A has partiallyreturned to the substantially straight configuration. In particular, thedistal deflectable section 16A of the catheter shaft is no longer in thefully-deflected configuration shown in FIGS. 33 and 35. Rather, thedistal deflectable section of the catheter shaft is in apartially-deflected configuration shown in FIGS. 37 and 39.

Referring next to FIGS. 40-43, when the plunger assembly 12B issubsequently returned to its neutral position (i.e., when the plungerassembly is fully retracted into the handle housing 14C as shown to thebest advantage in FIGS. 41 and 43), the actuation boss 48A extendingproximally from the plunger cap 30C presses the lever 46B proximally,which tensions the inactive deflection element 56A, which pulls thedistal deflectable section 16A of the catheter shaft 18A into asubstantially straight configuration shown in, for example, FIGS. 40 and42.

In all of the active return-to-straight mechanisms described above inconnection with FIGS. 11-43, the physician need only actuate a singlemechanism to not only create a desired amount of shaft deflection, butalso to fully return the catheter shaft to a substantially straightconfiguration.

FIG. 44 depicts a fourth embodiment for actively returning the distaldeflectable portion of a catheter shaft 18A to a substantially straightconfiguration through interaction with a single user actuator 116. Inparticular, FIG. 44 shows a plunger-type actuator 12C and a fragment ofa catheter shaft 18A. In FIG. 44, a pull wire 56B (other than the pullwire used to deflect the distal deflectable section of the cathetershaft) is shown in solid lines extending around a wire lateraldeflection pin 100 to a wire anchor 102. In this configuration, thelateral deflection pin 100 and the wire anchor 102 are located onopposite sides of the catheter longitudinal axis 40A, and the wireanchor is located proximal to the lateral defection pin. A wirelongitudinal deflection pin 104 is also shown in solid lines. This wirelongitudinal deflection pin is mounted to the handle housing, whereasthe lateral wire deflection pin 100 moves with the plunger assembly 12C.

Still referring to FIG. 44, in a first configuration, the plungerassembly is fully extended from a handle housing 14D, which would placethe distal section of the catheter in a fully-deflected configurationsimilar to that shown in, for example, FIGS. 3, 13, and 35. When, on theother hand, the plunger is placed in its fully-retracted configuration,the pull wire would follow the path shown in dashed lines around thewire lateral deflection pin 100 (shown in FIG. 44 as a dashed circle)and the wire longitudinal deflection pin 104 (also shown in FIG. 44 as adashed circle). As may be discerned from a review of FIG. 44, the wirepath is longer when the plunger assembly is in its fully-retractedconfiguration then when the plunger assembly in its fully-extendedconfiguration. Thus, the depicted pull wire 56B is tensioned when theplunger assembly is in its fully-retracted configuration. Thistensioning of the noted pull wire may be used to pull the distaldeflectable section of the catheter shaft to a substantially straightconfiguration similar to that shown in, for example, FIGS. 18 and 40.

FIG. 45 schematically depicts the distal deflectable section of thecatheter shaft in a substantially-straight configuration (solid lines),in a partially-deflected configuration (lines created from shortdashes), and in a hypothetical, fully-deflected configuration (linescreated from long dashes). An inactive deflection element 56C is shownin solid lines extending from a first anchor point or connection 106(located distal on the catheter shaft) to a secondary or fine returnactuator 108. Similarly, an active deflection element 22A is shownextending from a second anchor point or connection 110 (located distalon the catheter shaft) to a primary or gross return actuator 112comprising part of a deflection actuator 114, both of which a useractivates via the user actuator 116. Although the anchor points 106, 110are depicted for simplicity in FIG. 45 as being located at the samelongitudinal position along the catheter shaft, these deflectionelements need not be coupled or attached at the same distal location orto the same pull ring or other anchor points. Also, each anchor point106,110 that is schematically represented in FIG. 45 could be, forexample, a location where a pull wire is attached (e.g., by crimping orwelding) to, for example, a pull ring mounted or formed in a distalportion of a catheter shaft.

As also shown in FIG. 45, the fine return actuator 108 is automaticallyand directly triggered by the gross return actuator 112. This isschematically represented in this figure by the “Trigger” line 118connecting the “gross return actuator” box 112 to the “fine returnactuator” box 108. This schematically represents what occurs in theembodiments shown in, for example, FIGS. 11-43. When the deflectionactuator is fully actuated, the distal deflectable section of thecatheter is deflected by the angle phi (Φ) from the longitudinal axis40A of the substantially straight catheter. This angle may be selectedto meet the needs of the physician, but it is depicted in FIG. 45 asbeing approximately 45 degrees. This angle phi (Φ) also corresponds tothe angle phi (Φ) shown in, for example, FIG. 3.

As also shown in FIG. 45, when the deflection actuator 114, acting as agross return actuator 112, is returned to its neutral position, thecatheter shaft may not return to its fully-straight configuration.Rather, the catheter shaft may remain slightly offset from straight byan angle theta (θ). Then, in order to return the distal deflectablesection of the catheter shaft to its fully-straight orsubstantially-straight configuration, a secondary or fine returnactuator 108 may be actuated. As mentioned, in the configurationschematically depicted in FIG. 45, the fine return actuator 108 isautomatically triggered by the gross return actuator 112 being returnedto its neutral position.

FIG. 46 is similar to FIG. 45, but schematically represents embodimentswhere the fine return actuator 108A is actuated by the user, but notnecessarily directly by the gross return actuator 112A. The embodimentdepicted in FIG. 44 behaves in the manner depicted in FIG. 46. Stillother manners of initiating the fine return actuator are contemplated bythe present disclosure, such as, for example, using a sensor or sensors(not shown) to detect a position of the gross return actuator and/oruser actuator, and triggering the fine return actuator when the sensedposition indicates that the gross return actuator and/or user actuatorhas exhausted or sufficiently slowed its ability to continue returningthe catheter towards its neutral position. For example, a sensor couldbe located in the handle cap (see, for example, element 78 in FIG. 48)that could sense the position of the plunger body (see, for example,element 68 in FIG. 48) via, for example, a sensible feature mounted inor on the plunger body.

Referring next to FIGS. 47-58, an active return-to-straight mechanismaccording to another embodiment and comprising multiple user actuatorsis described next. In FIGS. 47-50, the primary actuator 12D has beenfully actuated, thereby placing the deflectable distal section 16A ofthe catheter shaft 18A in a fully-deflected configuration shown to bestadvantage in FIGS. 47 and 49. When the primary actuator 12D is in thisfully-actuated configuration, the thumb boss 36 has been pusheddistally, separating the thumb boss from the handle cap 78 as shown togood advantage in FIGS. 48 and 50. As also depicted in FIGS. 48 and 50,a secondary, manual return-to-straight slider 120 is in its ‘off’ orunactuated position.

In FIGS. 51-54, the primary actuator 12D has been returned to a neutralposition (fully-retracted position), but the secondary, manual,return-to-straight slider 120 remains in the ‘off’ position. Thus, thecatheter distal deflectable section 16A remains in a slightly-deflectedconfiguration as shown to good advantage in FIGS. 51 and 53. ComparingFIG. 52 to FIG. 48, or FIG. 54 to FIG. 50, it is apparent that theplunger assembly 12D has been retracted in FIGS. 52 and 54.

In FIGS. 55-58, the plunger assembly 12D remains in the same neutralconfiguration shown in FIGS. 51-54. However, in the configuration shownin FIGS. 55-58, the secondary, manual return-to-straight slider 120 hasbeen actuated (i.e., pulled proximally to the ‘on’ position), therebypulling the catheter tip portion 16A to a substantially-straightconfiguration shown to good advantage in FIGS. 55 and 57. Thisreturn-to-straight mechanism achieves some of the advantages previouslydescribed, but requires activation of a second actuator.

FIGS. 59-70 are similar to FIGS. 47-58, respectively, but disclose adifferent embodiment of an active return-to-straight mechanism. In FIGS.59-62, the primary actuator 12E is in a fully-actuated configuration,which pulls the distal deflectable section 16A of the catheter shaft 18Ainto its fully-deflected configuration shown in FIGS. 59-62. FIGS. 59,60, and 62 show the plunger assembly 12E (i.e., the primary actuator) inits fully-extended configuration, which results in the fully-deflecteddistal tip 16A section shown in FIGS. 59 and 61.

In FIGS. 63-66, the plunger assembly 12E has been returned to a neutralposition (i.e., the plunger assembly has been fully retracted into thehandle housing). The secondary actuator 122, which is the manual,return-to-straight knob 122, remains in the ‘off’ position. That is,comparing FIG. 64 to FIG. 60, or FIG. 66 to FIG. 62, it is possible tosee that the manual, return-to-straight knob remains in the ‘off’position despite the fact that the plunger assembly has been moved fromits fully-actuated configuration to its neutral position. Despite thefact that the plunger assembly is in its neutral position, the distaldeflectable section 16A of the catheter shaft may remain in aslightly-deflected configuration as shown in FIGS. 63 and 65. Uponmanually activating the return-to-straight mechanism to the ‘on’position represented in FIGS. 68 and 70, the inactive deflection elementis tensioned, thereby pulling the distal section 16A of catheter shaft18A to the substantially-straight configuration shown to best advantagein FIGS. 67 and 69.

Catheter manufactures may make a single catheter shaft for use on bothbi-directional and uni-directional catheters. This may, for example,simplify manufacturing processes and inventory. Such ‘dual-use’ cathetershafts may include two deflection elements or pull wires. In abi-directional catheter, both deflection elements are active. In auni-directional catheter, such as the uni-directional catheters depictedand described throughout this disclosure, only one of the deflectionelements may be active. However, in the embodiments described herein,the presence of the inactive deflection element is leveraged to activelyreturn the distal deflectable catheter shaft section to a substantiallystraight configuration during a medical procedure.

Embodiments are described herein of various apparatuses, systems, and/ormethods. Numerous specific details are set forth to provide a thoroughunderstanding of the overall structure, function, manufacture, and useof the embodiments as described in the specification and illustrated inthe accompanying drawings. It will be understood by those skilled in theart, however, that the embodiments may be practiced without suchspecific details. In other instances, well-known operations, components,and elements have not been described in detail so as not to obscure theembodiments described in the specification. Those of ordinary skill inthe art will understand that the embodiments described and illustratedherein are non-limiting examples, and thus it can be appreciated thatthe specific structural and functional details disclosed herein may berepresentative and do not necessarily limit the scope of allembodiments.

Reference throughout the specification to “various embodiments,” “someembodiments,” “one embodiment,” or “an embodiment,” or the like, meansthat a particular feature, structure, or characteristic described inconnection with the embodiment(s) is included in at least oneembodiment. Thus, appearances of the phrases “in various embodiments,”“in some embodiments,” “in one embodiment,” or “in an embodiment,” orthe like, in places throughout the specification, are not necessarilyall referring to the same embodiment. Furthermore, the particularfeatures, structures, or characteristics may be combined in any suitablemanner in one or more embodiments. Thus, the particular features,structures, or characteristics illustrated or described in connectionwith one embodiment may be combined, in whole or in part, with thefeatures, structures, or characteristics of one or more otherembodiments without limitation given that such combination is notillogical or non-functional.

It will be appreciated that the terms “proximal” and “distal” may beused throughout the specification with reference to a clinicianmanipulating one end of an instrument used to treat a patient. The term“proximal” refers to the portion of the instrument closest to theclinician and the term “distal” refers to the portion located furthestfrom the clinician. It will be further appreciated that for concisenessand clarity, spatial or directional terms such as “vertical,”“horizontal,” “up,” “down,” “clockwise,” and “counterclockwise” may beused herein with respect to the illustrated embodiments. However,medical instruments may be used in many orientations and positions, andthese terms are not intended to be limiting and absolute.

Joinder references (e.g., affixed, attached, coupled, connected, and thelike) are to be construed broadly and may include intermediate membersbetween a connection of elements and relative movement between elements.As such, joinder references do not necessarily infer that two elementsare directly connected and in fixed relation to each other. As usedherein, joinder references may also include two components that aremolded as a single or unitary piece. Changes in detail or structure maybe made without departing from the spirit of the invention as defined inthe appended claims.

What is claimed is:
 1. An apparatus, comprising: a deflection actuatorconfigured to cause deflection of a distal portion of a catheter from aninitial position; a first return actuator configured to partiallyreverse the deflection of the distal portion of the catheter; and asecond return actuator configured to continue reversing the deflectionof the distal portion of the catheter towards the initial position. 2.The apparatus of claim 1, wherein the first return actuator is coupledto the second return actuator, and wherein the second return actuator isconfigured to continue reversing the deflection of the distal portion ofthe catheter in response to the first return actuator reaching apositional threshold.
 3. The apparatus of claim 1, further comprising atleast one sensor coupled to the first return actuator and configured todetermine a positional threshold of the first return actuator, andfurther configured to initiate the second return actuator in response tothe first return actuator reaching the positional threshold.
 4. Theapparatus of claim 1, further comprising a first strand coupled betweenthe deflection actuator and the distal portion of the catheter, whereinactuation of the deflection actuator places the first strand in tensionto cause the distal portion of the catheter to deflect from the initialposition.
 5. The apparatus of claim 4, further comprising a firstconnection of the first strand and the distal portion of the catheter,where the first connection is positioned on a side of the cathetercorresponding to the direction of the deflection.
 6. The apparatus ofclaim 4, wherein the deflection actuator and the first return actuatorare commonly embodied on a plunger device, and wherein actuation of thedeflection actuator comprises distal actuation of the plunger device,and actuation of the first return actuator comprises proximal actuationof the plunger device.
 7. The apparatus of claim 4, further comprising asecond strand coupled between the second return actuator and the distalportion of the catheter, wherein actuation of the second return actuatorplaces the second strand in tension to cause the distal portion of thecatheter to continue reversing the deflection of the distal portion ofthe catheter towards the initial position.
 8. The apparatus of claim 7,further comprising: a first connection of the first strand and thedistal portion of the catheter, where the first connection is positionedon a first side of the catheter corresponding to the direction of thedeflection; and a second connection of the second strand and the distalportion of the catheter, where the second connection is positioned on asecond side of the catheter corresponding to a direction generallyopposite of the deflection.
 9. The apparatus of claim 1, furthercomprising a handle housing configured to house the deflection actuator,first return actuator, and second return actuator.
 10. A deflectablecatheter comprising the following: a catheter shaft comprising thefollowing: a shaft proximal end, a shaft distal end, a shaft deflectabledistal portion, and first and second tension members extending from theshaft proximal end to the shaft deflectable distal portion; a deflectionactuator operatively coupled to the first and second tension members,wherein the deflection actuator comprises an active return-to-straightmechanism comprising (i) a primary or gross return actuator and (ii) asecondary or fine return actuator; and a handle housing, wherein thedeflection actuator is at least partially mounted in the handle housing.11. The deflectable catheter of claim 10, wherein the primary returnactuator is configured to automatically trigger the secondary returnactuator.
 12. The deflectable catheter of claim 10, wherein the primaryreturn actuator is operatively coupled to the first tension member, andthe secondary return actuator is operatively coupled to the secondtension member.
 13. The deflectable catheter of claim 12, wherein thesecondary return actuator comprises a lever and an activation boss. 14.The deflectable catheter of claim 13, wherein the lever is pivotallymounted on the primary actuator, and wherein the actuation boss isaffixed to the handle housing.
 15. The deflectable catheter of claim 13,wherein the lever is mounted for movement relative to the primaryactuator, and wherein the actuation boss is affixed to the handlehousing.
 16. The deflectable catheter of claim 13, wherein the lever ispivotally mounted on the handle housing, and wherein the actuation bossis affixed to the primary actuator.
 17. The deflectable catheter ofclaim 13, wherein the lever is mounted for movement relative to thehandle housing, and wherein the actuation boss is affixed to the primaryactuator.
 18. The deflectable catheter of claim 13, wherein the lever isattached to the second tension member via a tuner and a tuner drum. 19.The deflectable catheter of claim 12, wherein the secondary returnactuator comprises a lever and an actuation boss, wherein the actuationboss is configured to actuate the lever from an unactuated configurationto an actuated configuration, and wherein the lever is adapted totension the second tension member when the lever is actuate.
 20. Thedeflectable catheter of claim 10, wherein the deflection actuator isoperable to variably deflect the shaft deflectable distal portion to apredetermined maximum deflection angle relative to a shaft longitudinalaxis extending between the shaft proximal end and a deflectioncommencement point located at a proximal end of the shaft deflectabledistal portion; wherein the primary return actuator is operable tovariably return the shaft deflectable distal portion to an offset anglerelative to the shaft longitudinal axis, the offset angle being lessthan the predetermined maximum deflection angle; and wherein thesecondary return actuator is operable to variably return the shaftdeflectable distal portion from the offset angle and into alignment withthe shaft longitudinal axis.
 21. The deflectable catheter of claim 10,wherein said deflection actuator comprises a plunger assembly that isslidably supported by at least one sleeve bearing mounted to the handlehousing, wherein the secondary return actuator comprises a lever and anactivation boss, and wherein the lever is pivotably mounted to aproximal end of the plunger assembly.
 22. The deflectable catheter ofclaim 10, wherein the deflection actuator is adapted to be variablyactuated between (A) a neutral configuration wherein the deflectionactuator is not actively deflecting the shaft deflectable distalportion, and (B) a fully-actuated configuration wherein the deflectionactuator is actively deflecting the shaft deflectable distal portion toa maximum set deflection angle; and wherein the activereturn-to-straight mechanism is adapted to be automatically actuated toplace the shaft deflectable distal portion in a substantially straightconfiguration as the deflection actuator is returned to the neutralconfiguration.
 23. The deflectable catheter of claim 10, wherein thesecondary return actuator comprises a pin affixed to the handle housingand configured to alter a path length of the second tension member. 24.The deflectable catheter of claim 10, wherein the secondary returnactuator comprises a manual actuator.
 25. The deflectable catheter ofclaim 24, wherein the secondary actuator comprises a knob or lever.